You need to "pull" the chicken into little pieces. What you do is hold the breast in place with a fork. Pulling against the grain, use a fork to rip little pieces of chicken off the main piece. If you have a fast connection, look at this short Pulling Chicken Video (3mb) for a visual aid.

Lay a low carb tortilla on a plate. Make a line of the pulled chicken above the center line of the tortilla. Drizzle half of the sauce down the line. Sprinkle on a quarter of the shredded Mexican cheese on top, and sprinkle water on top to help it moisten.

Microwave for 20 seconds to soften the shell. Roll up the sides and sprinkle another 1/4 of the cheese on top. Microwave 1 1/2 minutes on high. Do the same with a second tortilla. Garnish with sour cream, diced tomato and lettuce if desired.